1. Field of the Invention
The present invention relates to an optical lens system, and more particularly to a five-piece optical lens system applicable to electronic products.
2. Description of the Prior Art
With the consumer electronic industry continuously growing, the current market demand for small imaging lens system is also increasing. Especially for the imaging lens application in mobile phone, tablet computer and notebook, optical lens system has almost become mainstream in the market. Optical lens has been developed into multiple-piece lens system from the early two-piece lens system, in order to enhance resolution and image quality. Moreover, as electronic products are becoming thinner, lighter and easier to carry, the imaging lens system also needs to be further reduced in size in order to fit in the increasingly miniaturized carrier, meanwhile, it would be better to have a smaller F number, so that the imaging lens system is still able to take clear pictures even when the light is dim. For example, the optical lens systems disclosed in U.S. Pat. No. 8,310,768, 8,395,851 or 8,456,757 are all provided with multiple pieces of lens elements in order to improve resolution, however, their lengths are too long and F numbers are big. For another example, the optical lens systems disclosed in U.S. Pat. Nos. 8,284,291, 8,390,941 and 8,488,259 all have a smaller F number, but is provided with more than two lens elements which are made of high refractive material, and the use of high refractive material will increase the manufacturing cost. Yet, for another example, the optical lens system as disclosed in U.S. Pat. No. 8,456,758, only uses a single high refractive material piece and provides a smaller F number. However, the chief ray angle at the edge of the image is too large, which adversely affects the brightness and color at the peripheral of the image, namely, resulting in a poor image edge quality.
The present invention has been made in order to solve the above-mentioned problems.